Solids/liquids separation is an art which has been practiced for centuries. Traditionally, solids have been removed from liquids such as water for purposes of clarifying the liquid. Separation is effectuated using agents such as coagulants, flocculants, or combinations of coagulants and flocculants.
Traditionally, these agents have been water soluble. They have been added by one of the following methods: by dissolving the polymer in water and adding the resulting solution to the water to be clarified, or by suspending a water soluble polymer containing hydrophilic monomers in an oil external phase dispersion or emulsion which is inverted in the water to be clarified.
The use of aqueous solutions of a polymer present a number of difficulties. The most significant being that the solution many times becomes extremely viscous with even low concentrations of polymer. Concentrations in excess of 1 or 2 weight % may be impossible to feed.
Oil external systems also have many disadvantages. Oil is immiscible with water. When the polymer in oil is spilled onto a wood surface it creates both a fire hazard and a slip and fall hazard. Additionally, these systems have a tendency to promote gellation of the polymer. When this happens, the polymer gel is not available to the system being treated. Thus under-feeding and, unexpected, inferior treatment can result.
Other disadvantages of oil dispersed polymers (i.e. oil continuous phase polymers) exist. They usually become increasingly more viscous upon aging. Viscosity hinders the application of the polymer to the system.
Also oil splits occur. That is the oil external dispersion in time will separate, the dispersed polymer will settle to the bottom of the vessel and the oil layer will rise to the top.
It would be advantageous to develop a polymer composition and method of feeding that composition which would overcome the above difficulties presently experienced. In particular, it would be advantageous to use a method in which a relatively high concentration of polymer can be added to the system being treated for solids/liquids separation. It would be advantageous to provide that polymer in a form where separation from the external phase is minimized. And it would be advantageous to provide that polymer in a form where gellation or viscosity problems are minimized.